Disk controlling method and apparatus for transferring a record from a disk to a host via an intermediate buffer

Abstract

A disk controlling apparatus creates sense data indicating the contents of an error and writes it into an intermediate buffer provided within the disk controlling apparatus together with the record normally read when a key portion or a data portion constituting a record is not normally read. The disk controlling apparatus searches the intermediate buffer for desired record, reads and informs an error while taking the sense data into consideration for each record. The disk controlling apparatus stores a write address in a memory at the time of writing data, and when data are normally written the write address is eliminated from the memory, while holding the address when data are not normally written. At the time of reading data, if the address which agrees with the read address is stored in the memory, the disk controlling apparatus reports an error to a host apparatus. The disk controlling apparatus further calculates the busy ratio indicating the rate at which each channel adapter is used for I/O processing, and data is transmitted and received to and from the host apparatus through the channel adapter which has the lowest busy ratio.

What is claimed is: 
     
       1. A disk controlling method by a disk controlling apparatus provided between a host apparatus and a disk apparatus so as to store a record of a CKD format read from said disk apparatus into an intermediate buffer provided in said disk controlling apparatus, search said intermediate buffer for desired data and transfer said desired data to said host apparatus, said disk controlling method comprising the steps of: monitoring whether or not a key portion or a data portion are normally read from said disk apparatus when said record of a CKD format read from said disk apparatus is written into said intermediate buffer; and   when said key portion or said data portion is not normally read,   creating sense data indicating the contents of an error,   writing said sense data in the area in said intermediate buffer in which said key portion or said data portion is to be written in place of said key portion or said data portion,   creating control information indicating that said sense data is written in said area,   writing said control information for each record at a predetermined position of said intermediate buffer,   searching for the record designated by a search command input from said host apparatus without outputting an error due to said sense data when said search command is a command for searching an area other than the area in which said sense data is stored,   judging whether or not said sense data is written in the area which is to be searched in accordance with a search command or a read command input from said host apparatus by reference to said control information for each record; and   reporting said sense data as error information to said host apparatus if said sense data is written in said area.   
     
     
       2. A disk controlling method according to claim 1, wherein said sense data is written in the area referred to as key area in said intermediate buffer in which said key portion is written when said key portion is not normally read, while said sense data is written in the area referred to as data area in said intermediate buffer in which said data portion is written when said data portion is not normally read. 
     
     
       3. A disk controlling method according to claim 2, further including the steps of: creating control information so that said control information can manifest whether said sense data is written in said key area or said data area;   judging for each record whether or not said sense data is written in said key area by reference to said control information when a command for searching said key area is input from said host apparatus; and   reporting said sense data to said host apparatus as error information if said sense data is written in said key area.   
     
     
       4. A disk controlling method according to claim 2, further including the steps of: creating control information so that said control information can manifest whether said sense data is written in said key area or said data area;   judging for each record whether or not said sense data is written in said data area by reference to said control information when a command for searching said data area is input from said host apparatus; and   reporting said sense data to said host apparatus as error information if said data is written in said data area.   
     
     
       5. A disk controlling method by a disk controlling apparatus provided between a host apparatus and a disk apparatus so as to write data of a CKD format into said disk apparatus in accordance with a write command from said host apparatus and read said data of the CKD format from said disk apparatus in accordance with a read command from said host apparatus and transfer said data to said host apparatus, said control method comprising the steps of: storing a write address for said disk apparatus into a memory at the time of writing said data;   eliminating said write address when all of said data of the CKD format are normally written, and holding said write address without eliminating it when a write error is caused after a part of said data are written;   judging whether or not the address which agrees with the read address is stored in said memory at the time of reading said data of the CKD format; and   informing said host apparatus of an error when said address is stored in said memory, while reading said data of the CKD format at said address when said address is not stored in said memory.   
     
     
       6. A disk controlling method according to claim 5, wherein said memory is composed of a storage means which does not lose the contents of memory even if the power supply is cut. 
     
     
       7. A disk controlling method according to claim 5, further comprising the steps of: judging whether or not the write address is stored in said memory when said data of the CKD format are normally written; and   eliminating said write address from said memory if it is stored.   
     
     
       8. A disk controlling apparatus provided between a host apparatus and a disk apparatus, comprising: a channel adapter serving as an interface between said host apparatus and said disk controlling apparatus;   a device adapter serving as an interface between said disk controlling apparatus and said disk apparatus;   a resource manager for controlling the resource management as a whole and the processing operations;   an intermediate buffer for storing data of a CKD format which are read from said disk apparatus; and   a service adapter for detecting a trouble caused in one of the units which are connected to each other by a bus; wherein said device adapter includes:   sense data creating means for creating sense data when a key portion or a data portion is not normally read from said disk apparatus at the time of writing said data of the CKD format from said disk apparatus into said intermediate buffer;   writing means for writing said sense data in the area in said intermediate buffer in which said key portion or said data portion is to be written in place of said key portion or said data portion;   means for creating control information indicating that said sense data is written in said area; and   writing means for writing said control information at a predetermined position of said intermediate buffer; and   wherein said channel adapter includes:   data search/transfer means for searching said intermediate buffer for desired data and transferring said data to said host apparatus, said data search/transfer means including:   means for searching for the record designated by a search command input from said host apparatus without outputting an error due to said sense data when said search command is a command for searching an area other than the area in which said sense data is stored;   means for judging whether or not said sense data is written in the area which is to be searched in accordance with a command input from said host apparatus by reference to said control information for each record; and   means for reporting said sense data as an error to said host apparatus if said sense data is written in said area.